1. Field of the Invention
The present invention relates to an in-vehicle audio device and an in-vehicle audio system.
2. Description of Related Art
There is known an in-vehicle audio device for playing back music data stored in a storage medium such as CD (compact disk), MD (mini disk), HDD (hard disk drive) and the like, and for outputting the played-back sound from a speaker. There is also known a portable audio terminal (e.g., a portable audio player) capable storing huge music data and playing back music data.
In recent years, a technique has been proposed for the in-vehicle audio device to play back music data stored in the portable audio terminal carried into a vehicle. For example, Patent Document 1 discloses an audio system for a vehicle. In the audio system, when multiple portable audio terminals (i.e., multiple portable audio devices) are carried into the vehicle, transmission of music data is performed between the multiple portable audio terminals and the in-vehicle audio device by wireless communication in the vehicle, and the in-vehicle audio device plays back the music data stored in respective portable audio terminals.
According to Patent Document 1, when a portable audio terminal and the in-vehicle audio device recognize and authenticate each other to configure a network, the in-vehicle audio device can display a list of tracks of the music data stored in the currently-connected portable audio terminal on a portable audio terminal basis. Further, when a track is selected from the list of tracks and when an in-vehicle speaker is selected as a sound output device, the music data of the selected track is played back and outputted.
Patent Document 1: JP 2001-296875A corresponding to US 2001/0048749A
The inventor of the present application has found out that the technique disclosed in Patent Document 1 involves the following difficulty. For example, when multiple portable music terminals carried into the vehicle are incapable of simultaneously having connection with the in-vehicle audio device, the in-vehicle audio device can display a list of tracks stored in one currently-connected portable music terminal but cannot display a list of tracks stored in another currently-unconnected portable audio terminal: Thus, the music data stored in the unconnected portable audio terminal cannot selected from the list displayed in the in-vehicle audio device and cannot be played back by the in-vehicle audio device in this situation. Therefore, the technique disclosed in Patent document 1 involves lack of usability.